Funny thing as a fact, once leaving the checkpoint on the
non-diverted route, all the way to Kranji MRT (cannot run on a 90
degrees turn), and then after Kranji MRT all the way to Bt Panjang,
the BC can run at 60-80 km/h, with sections hitting to 90 plus if
the bus can do it mechanically.
To a China or seasoned s178 BC, no road is too narrow for them.
I mean trips at 2200 and after. Daytime different because of more
cars on the roads.
I would recommend, well not very useful anyways cause its a
obviously a bus with an obvious positive rating: SBS997A.
Reason? Smooth engine performance. Not talking about the special
points because its a special bus... 
If you're looking for a S171 bus that does not have speed limiter,
TIB 507M is all yours. 
Downslope + SL trying to overtake S138 Mercedes at
Mandai (and therefore stepping hard on the accelerator), hit
89km/h (with the speedometer needle almost touching 90).
Funny thing is that they lock most of the S171 buses with speed
limiter, or not those dee-dee-dee sounds. Then the journey times
stretches. =.="
But good thing is that AMDEP tuned quite a fair number of the
S171 buses to hit higher RPM before changing the gear (ZF), so that
they can accelerate faster.
